New power couple alert: Leonard Lauder — the billionaire chairman emeritus of Estée Lauder — has been quietly dating Linda E. Johnson, the much younger president and CEO of the Brooklyn Public Library, Page Six can exclusively reveal. The two were spotted ringing in 2013 together at the Metropolitan Opera’s New Year’s Eve Gala. Spies say Lauder, 79, was also seen back in November with his arm around Johnson, 54, at a French-American Foundation gala, and later at an opening of the Museum of Arts and Design’s “The Art of Scent” exhibition. Lauder’s wife, Evelyn, died in 2011 at 75. Social spies say his new romance has dashed the hopes of numerous New York socialites of a certain age since Lauder, reportedly worth a cool $7.9 billion, is one of the town’s most eligible bachelors. Johnson was formerly head of the National Constitution Center. (She’s also apparently fit: According to a library bio, she’s run seven marathons.) An Estée Lauder rep said, “We don’t comment on Mr. Lauder’s personal life.” A Brooklyn Library rep had no comment.